Field of the Invention
The present invention relates to ball rebounding devices, and more particularly to rebounding systems in which a tensioning device pulls the net taut within a frame.
Related Art
Ball rebounding devices are used for many sports. Most ball rebounding devices use bungee cords or some other spring mechanism to hold nets and other fabrics within the frame, such as in U.S. Pat. Nos. 2,992,002, 4,489,941, 5,833,234 and 6,299,544 while other ball rebounding devices have a flexible margin between the net and the frame, such as in U.S. Pat. Nos. 5,615,889 and 4,082,271. However, these spring elements and flexible margins reduce the overall tension in the net, thereby reducing the rebound effect of the rebounding device, i.e., the amount of a ball's potential energy, or other projectile, that is converted into kinetic energy when the projectile hits the net. Conversion of the potential energy is lost through the springs. Additionally, these known systems lose their rebounding capacity over time as the spring mechanisms or other flexible margins rotate through thousands of expansion and contraction cycles in response to balls being thrown against the nets. The spring-supporting frames of these known rebounders are much more rigid than the springs that hold the nets and do not provide any additional spring flexibility or spring-loading into the overall rebounding system.
Some ball rebounding devices have a rigid margin within an outer frame and have eliminated the springs between the rigid margin and the frame, such as in U.S. Pat. No. 6,209,877 and US Patent App. Pub. No. 2012/0208658, and while these inner/outer frame systems have the capability to pull much higher tensions through the net, their designs are inefficient. In particular, previously known inner/outer frame systems limit the size of the net's cells and the locations in which the net's cells can connect to the inner frame based on the locations of connection elements, such as through-holes for lacing the net's cells or knobs for holding the net's cells. Additionally, these known inner/outer frame systems require the inner frame to be pulled toward the outer frame by individual fasteners that are distributed between the lengths of the frames and do not allow the entire inner frame to be pulled in whole toward the outer frame, simultaneously along the entire length. This inefficiency in the pulling reduces the overall tension that can be obtained and increases the time and cost of manufacturing.
The designs of double-frame systems are also rather inflexible and rigid in order to maintain an equal distance between the inner frame and the outer frame along the length of the frames. They do not provide a flexible outer frame, and the inner frame portions of these known inner/outer frame systems are uniquely designed for their respective outer frames and cannot be used to replace the spring and net systems found in most existing rebounding devices. Accordingly, none of the prior ball rebounding devices could be used as a retrofit system that would be able to be used within existing spring-supporting frames because these frames are only designed to support the lower tensions produced by bungees or other spring mechanisms, and these frames cold not support the higher tensions in these double-frame systems. Also, many of these double-frame systems have holes that must be drilled through the outer frame at particular locations in order to hold the inner frame, and if these holes were to be drilled into the spring-supporting frames, it would further reduce their support capacity and may even compromise the structural integrity of the spring-supporting frames.
There remains a need for a ball rebounding device that can create high tension in nets and can be used with different types of nets, including nets that have different sized cells. It would be another benefit for a ball rebounding system to have structural features which allow for faster and more efficient assembly methods. It would be an additional benefit for a ball rebounding system to be capable of retrofitting the nets and springs or fasteners in existing ball rebounding frames with replacement nets, tension rods and fasteners according to the present invention to provide a better rebound effect or to retrofit the existing frames with an entire frame-rod-net system that can be installed without compromising the structural integrity of the existing frames. It would be another benefit to retrofit the nets in a manner that is less time consuming than the process necessary to install the original nets. It would be another benefit for a ball rebounding system to have a frame which deflects with a spring action as tension is pulled on the net being held in place by the frame.